Lecture #11


term for processes in which no heat energy is added or removed, but in which the temperature changes

warm/less dense air (lighter)


cold/denser air (heavier)


as a parcel of air rises

-it expands (volume changes)
-it comes under less and less pressure as it rises in the atmosphere and thus expands
-as the air expands, the molecular action (kinectic energy) decreases and thus the temperature decreases

expanding air

= temperature decreases

compressing air

= temperature increases

Adiabatic Temperature Change

changing the temperature of the air without adding or subtracting heat (simply the result of compressing the air or allowing it to expand)

P (mb) = T ( ° K) x p (kg/m3) x C (2.87)

at the surface as temperature decreases, density and pressure increases; as the temperature increases, air density and pressure decreases

rate of adiabatic change

the rate at which the air temperature changes as it rises or falls through the atmosphere

dry adiabatic rate (DAR or DALR)

-when air is unsaturated (air temperature > dew point temperature; RH < 100% )
-the DAR is a constant rater of 1°C/100m or 10°C/1000m
-rising air cools at 1°C/100m (10°C/1000m)
-falling air warms at 1°C/100m (10°C/1000m)

wet or saturated adiabatic rate (SAR or SALR)

-when the air is saturated; air temperature = dew point temperature; RH = 100%
-the SAR is not a constant rate but a variable rate: 5°-9°C/100m

condensation level

height at which condensation occurs; where cloud formation begins (usually at the bottom of a cloud mass)

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

Voice Recording